Simple question,

Is it possible to install an AEM water injection fail safe to a Power FC so if the water/meth tank runs out or a line explodes, can the power FC retard timing or cut boost?

(I'm almost sure that I need a stand alone system for this kind of mod but thought I'd ask)

 

The power FC is a standalone but it's not powerful enough to accept inputs and then act on them in that way. A power fc doesn't care your oil pressure is 0, it will give you 15psi if you ask for it.

 

I see, that makes me sad

Respectfully, the power FC is a replacement and a stand alone is when you change the whole harness.

 

sorry but i was thinking about something else when i posted earlier and while the calcs were correct they didn't relate to water. they related to withdrawing a fuel type injectant.my mistake.

as to whether a failsafe is necessary it of course depends on how close you are to the "edge" as to tuning. most are tuned conservatively.

this does not mean AI is not needed for our 13BREWs... the water and or alcohol components delivers important interior cleaning. most of the motors that came in to me for rebuilding (around 160) had rotors caked with an oily carbon which encourages pre-igntion. the carbon on the rotor can act as a glow plug setting off pre-ignition which dishes rotors and then encourages follow-on detonation which breaks things..

here is a picture of a rotor that came from my personal motor after 4 years of usage. the rotor was not cleaned for the picture:


here is the typical non AI rotor



a combination of premix and richish AFRs with no AI creates a dangerous situation.

here's a comparison between my 4 year in service rotor and a typical incoming rotor. notice also the carbon behind the sideseals on the incoming rotor and no carbon behind the sideseals on my rotor. this is due to poor sideseal gap.


the cleaning effect of any AI system is profound and important to motor health.

i have run Ai since 2003 and never have had a delivery problem. many tanks do offer a low level light. you could easily place a pressure sensor in the line and run it through one of the Datalogit inputs.

 

Such a beautiful formula laid out. Thank you mr Coleman for that 👀👀

oh boy lol who told you that?

 

if you think outside the box there might be a way. you could probably get it to flash the knock warning or check engine light pretty easily

 

This is exactly why I want to do AI, for this exact reason. I always read what it can do but never seen pictures of it. Thank you for sharing. I'll probably end up doing 100% water because I'm not doing it for extra power but for better engine health. Also I wouldn't need a failsafe, now that I think of it because I'm not using the AI for tuning on the edge.

 

A book called Street Rotary wrote by an engineer, Mark Warner. Lol.

 

Very high chance you're missing some context because that doesn't make any sense. Maybe pre 2009 when it was being written and plug and plays werent so prevalent that was the case but it's not a true statement today.

Standalone, in this setting, is a relevant term to its counterpart: piggyback. A piggyback intercepts signals to a/the factory computer where as a standalone replaces it entirely. Back in the day when plug and play options weren't really a thing then yes, you would have to wire in these ecus to work which involves replacing the engine harness. So an ecu isn't not a standalone simply because you dont have to wire it in. It's like saying chickens aren't birds because they dont fly..... (that well)

something people in general need to keep in mind is literature is a product of the time it was written. When reading these things, especially technical publications, you need to be mindful of what era it was written vs what era YOU'RE in. At one time a map of the solar system had earth in the middle and that was true until it wasnt. At one time medical books said sperm swims like tadpoles, then further discoveries found this to not be the case.

Something of an extreme explanation but just so you dont go around saying things like that in the wild and people look at you funny. Like people who say the have a friend with a cammed rotary and larger valves 😒😒

 

Nah mannn ,

The order from least to greatest goes chip, piggyback, replacement, then stand alone.

It's called replacement because you are only replacing the ECU; it's called stand-alone because the added harness gives you more features since it's not utilizing the stock harness.

A Power FC and Haltech 2500 are in different categories. I'm sorry, man, but that's how the cookie crumbles. Lol. And I'm trying to save you from saying that in the wild, but honestly, it's not a big deal. Most people won't judge you off minor technical errors unless you're a rocket scientist talking to a client.

"Sir, we can use pure oxygen in our rockets again." (That's how Apollo 1 blew up)

 

The AEM failsafe gauge instructions claim it has a high-side output that can be configured to send 12V power out when things are normal and then shut it off when the flow is below expected. You could use this as the 12V power for the boost solenoid, assuming the vacuum lines are run in a way that no power would result in wastegate spring pressure. You can try unplugging your solenoid to test if the boost goes high or low, but be sure the overboost cut is set to something safe in case the boost goes high when the solenoid is unplugged. Once you've proven that works, you can use a soft wastegate spring and tune those sections of the maps for conservative fuel and timing.

I don't like the idea of tricking the ECU into a complete fuel or spark cut, if you can't trigger a rev limit or boost limit via the ECU's switch input pins I would rather light up a bright warning LED to warn the driver they should back off the throttle. Killing engine power completely can lose power steering and power brakes, which could be dangerous.

I agree with cr-rex about the term 'standalone ECU', it means the aftermarket ECU completely replaces the original one. A plug-in or plug-and-play standalone would be a special type of standalone that plugs into the factory harness, and some of those plug-in standalones will even re-use the original enclosure. This article from Dsport is a good rundown of the terms I've heard from most tuners and ECU manufacturers. https://dsportmag.com/the-tech/educa...nd-alone-ecus/

 

So there is a way, but it has to be rigged. I won’t do the fail-safe then because you’re right. It does seem dangerous.

Also, *clears throat*

Replacement ECU, “Like the name suggests, a replacement ECU is intended to take the place of the factory OEM box. The user simply unplugs and unbolts the OEM ECU from the vehicle, and then bolts and plugs in the aftermarket box. The new ECU is programmed from the factory with base fuel and ignition map, and also is configured to run the engine’s ancillary equipment (e.g., fans, etc.) just as the original ECU did. A handheld tuning “paddle” or laptop allows the user to make changes to the maps and tune to engine as required.” “The A’PEXi Power FC is a popular replacement ECU for the stock ECU on third-generation RX-7s”

Standalone EMS, “The tuner of a standalone usually also has to build a full custom engine electrical wiring harness. For these reasons, a standalone system is not generally recommended for the inexperienced; i.e., there is not generally a good reason to go this route unless the vehicle application requires complete and total adjustability.”

This is from the Mark Warner book, written in 2009, which is still new enough to reference the Power FC directly in his book as a replacement ECU. Again, this guy is an engineer and he’s no one to sneeze at.

 

not rigged, you just need to open your mind a bit. the ECU has ~76 pins, there are a bunch that would light the exhaust temp/check engine light, most of which aren't being used. how about the floor temp sensor?
harder would be some cut, Scotty's idea is better, turn off the boost solenoid...

 

Low possibility the book was written in 2009. It was PUBLISHED in 2009 but very likely written collectively in the years before that. Whose the say how far back other than the author....

Anyway, I'm going to take your response as trolling and exit this thread. I dont understand how you're so fixated on this. The persistence on my end to explain to you otherwise is the fact that you're understanding isn't completely accurate. you can avoid an embarrassing situation by not saying what you're saying. It doesnt make any sense.

Good luck though, seems you got a few possibilities for what you're trying to do

 

Lol so if I have a Haltech 2500 and I use the stock harness with an adaptor it's not a stand alone? Got it.

Little known fact for you Creepen: RX7 actually stands for Revs Times Seven, because it's got 5 forward speeds, with reverse and neutral. True story, go tell your friends.

Now I've had some fun, I do kinda understand Creepen's point. Power FC is application specific, so specific that different year FDs need different versions of the Power FC ECUs. I know Power FC supports different platforms (Supra, Celica, MR2), but again I think those are very much car by car, with only the commander shared between them. Does anyone know if the software and pins are the only difference between applications?

 

For me, I run AI as an added benefit AFTER tuning the car. I used Xavier Borgs software to dial in my car to 14.5psi. After I was happy with that I then added the AI as an added bonus to help clean the motor, lower intake temps and lower exhaust temps. I have my system coming on at 10psi+ running the 250cc needle.

I will say however that I upgraded to the V3 AEM nozzle roughly 16 months ago and exclusively ran distilled water. Recently I found that the tank was not any lower and come to find out that the rubber check valve in the V3 nozzle is NOT allowing anything to pass through. I called AEM, and of course this was the first time they had heard of the check valve going bad. Found it crazy that I maybe drive my FD 1000 miles a year and the nozzle is stuck shut.

The solution from AEM was to either buy a replacement V3 nozzle or remove the rubber check valve inside. Because I am using AI as an added benefit, I am going to just remove the rubber check valve and move on.

However if I tuned aggressively with the PFC and Water or Boost Juice, it could have easily put my motor in jeopardy. Moral of my story is that until I invest in a Haltec or more advanced hardware, simply use the AI AFTER tuning the car as an added benefit. If it fails, it does not put the motor at risk.

 

I personally just moved away from the PowerFC but there are ways to add failsafes outside of the ECU. scotty305 nailed a simple solution.

A few carefully selected hobbs switches and relays can provide some protection if you don't have a modern ECU. If you are really creative you don't even need hard cuts, you could trick the ECU by adding resistance to an existing sensor. Probably not great advice so I wont go any further, but creativity is key.

What I'm trying to say is if you cant afford new hardware, don't let the old stuff hold you back! I was running 6 injectors and some creative failsafes with my PowerFC.

 

"What I'm trying to say is if you cant afford new hardware, don't let the old stuff hold you back! I was running 6 injectors and some creative failsafes with my PowerFC."

absolutely.

 

Lol, I'm not trolling. I will come as far along as it's not a proper standalone. You're VERY limited on the stock harness. It's like having a computer with an i9 9900k, 32Gigs of Ram, and a 2080 GPU, but you're gaming on a monitor that only uses VGA. The spectrum between a power FC and a Haltech 2500 (with its added harness and sensors) is a big difference: the power FC shouldn't get the same credit as a true standalone. Now that adaptor harness is only for the 96-02 FD3S because it's for the 16 bit harness. I will call the Power FC a stand-alone replacement ECU from now on but it's not a true standalone.

Yes, thank you. This is what I was thinking about doing before I even asked the question. Nice to see someone else has done it.

So if my life depended on it, there is a way. That's nice to know but I'll wait until I upgrade my ECU. The only reason why I don't upgrade is because installing another harness is a big job. I wonder how big the job is compared too replacing all the stock vacuum hoses to the twin turbo. (That's the biggest job I've done personally)

 

It's actually quite simple. I use the 12V trigger on the AEM failsafe to send a signal to the Power FC to activate the #2 on the boost control found on Settings 1 page through a small relay providing ground. Remember the Power FC has the ability to set a second boost setting for low boost or no boost. The #1is your normal boost. Make the #2 setting numbers low to provide no boost. That's it. The tank runs out or if the pump pressure falls thenthe Power FC switches you to no boost. There will be a small amount of lag for the solenoids to lower the boost.

Here is the instruction for the Power FC manual:


E-5-2 Remote boost switch ^ • Change boost settings “on the fly” ƒ Check the Boost Switch (SW4) “check box” to enable the switch ƒ You must connect a switch to terminal “SW4” on the FC-Box {FC2 FC-Box 4 Switches} ƒ Connect the switch between “SW4” and ground • When switch is open boost setting one will be selected • When switch is closed boost setting two will be selected • Switch will not function if a single turbo boost kit is in use • If you enable the feature but don’t connect a switch, {A-1 Boost Control} will be set to Boost setting one


Mike